In containment vessels, such as those for crude oil, motor oils, alcohol, and various types of fuels, water can enter the vessel through contamination and condensation. Also, crude oil produced from wells often has some salt water content. Even if the water is first separated, some of the water will be entwined with the flow of crude oil into the containment vessel. A device is employed to determine the water level in the vessel, so that the water can be removed from the vessel and disposed of, leaving only pure fluids in the vessel. A preexisting method for determining the water level in a containment vessel requires applying a layer of chemical gauging paste by hand to a gauge line. The gauge line is then lowered into the vessel. Once the gauge line has reached the bottom of the vessel, an operator has to hold the gauge line steady for a period of time to allow the chemical gauging paste to activate and change colors depending on the fluid in contact with the paste. The gauge line must then be reeled up and the operator must look to see where the color changes on the gauge line to determine the water level in the tank. This method of gauging the water level in a containment vessel is inaccurate and time consuming.